Along with the physical dimension, the geometric shape significantly affects the electronic states of semiconductor nanostructures such as quantum dots or nanowires. Most nanowires are epitaxially grown on a patterned substrate and are oriented vertical to the substrate surface. For example, the growth of GaAs from an array of circular apertures patterned on a Si(111) substrate, the growth of GaN on a sapphire or a SiC substrate, and the growth of semiconductor nanowires by vapor-liquid-solid (VLS) are generally oriented vertical to the growth substrate. Problems arise when growth not vertical to the substrate is desired. For example, VLS wires are often removed from the growth substrate and repositioned at a different orientation on a second substrate. This is a difficult, low yield processing step, which considerably diminishes the density and practicality of nanowire devices and circuits.
Thus, there is a need to overcome these and other problems of the prior art and to provide in-plane nanowires, related nanowire devices, and methods for their formation along a growth substrate surface.